Ab initio studies of two Al grain boundaries subjected to mixed tension/shear mode loading: how shear may promote breakage

作者：Ehlers F J H^*; Seydou M; Tingaud D; Maurel F; Queyreau S; Charles Y

来源：Modelling and Simulation in Materials Science and Engineering, 2017, 25(6): 064001.

DOI：10.1088/1361-651X/aa7496

• aluminium
• grain boundary
• traction-separation curve
• density functional theory
• mixed mode loading

Using the framework of density functional theory, the structural and energetic response of two face-centred cubic (fcc) Al grain boundaries (GBs) to combined tension and shear loadings has been examined. It is shown that tension will serve to inhibit the Sigma 5 [100] 36.87 degrees twist GB response to shear in a mixed-mode loading scenario, by increasing the difference in structural environments for inequivalent atoms at the GB plane. We propose that the presence of such atoms, rather than the full structural details of the GB structure, is instrumental in triggering this tension-shear interplay. As support for this hypothesis, we compute the Sigma 3 [-110] (111) 60 degrees symmetric tilt GB mixed-mode loading response. Here, all atoms at the GB plane are equivalent, and the qualitative shear energy variation is unaffected by tension. Our findings indicate that general fcc Al GBs may display a stronger shear energy variation at larger levels of tension, contrasting general expectations. The implications to GB breakage are discussed.

• 出版日期2017-9-1